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What can be said of the water here? A) The river water is naturally clear, fed by snowmelt from the Colorado Rockies.B) The river water is kept clear by the Park Service to keep the trout healthy.C) The river was naturally muddy, but has been made clear because most of the sediment is settling outin the reservoir behind the dam upstream.D) The river was cleaned up briefly by the Park Service to help Stephanie and Topher in their filming.E) The river is really filled with 7-UP, hence the green color.Feedback: Native species that lived in the muddy waters are now in danger of becoming extinct, because the clear water released from the dam makes those fish too easy for predators to see.Points Earned: 1.0/1.0 Correct Answer(s):C
Submitted by WOLFENDALE, BRITTNEY (BLW5294) on 2/27/2013 4:44:30 PMPoints Awarded2.00Points Missed3.00Percentage40.0%1. Which of these materials is “hottest” in the sense that it is most likely to flow rather than to break (note thatK stands for Kelvin, an absolute temperature scale in which zero is absolute zero and higher numbers mean warmer temperatures):A) A material at 1000oK that melts at 2000oK.B) A material at 100oK that melts at 200oK.C) A material at 250oK that melts at 300oK.D) A material at 1001oK that melts at 12000oK.E) All are the same temperature.Feedback: Flowing rather than breaking becomes likely when a material is warmed more than halfway from absolute zero to the melting temperature. The case with 250oK here is warmed five-sixths of the way from absolute zero toward the melting point, and the others are only halfway or less. They are not all at the same temperature.Points Earned: 0.0/1.0 Correct Answer(s):C2. During the most recent ice age:A) Central Pennsylvania was overrun by ice from Canada.B) Central Pennsylvania was just beyond the edge of the Canadian ice.C) Central Pennsylvania was far from the nearest ice.D) Central Pennsylvania was overrun by ice from the south.E) We have no idea what central Pennsylvania was like.Feedback: This is just a fact of geography as described in the text; central Pennsylvania was near but beyond the edge of ice coming from the north. The last option, “no one knows”, is the last refuge of lazy minds, and not at all correct.Points Earned: 1.0/1.0 Correct Answer(s):B
3. Glaciers form where:A) The average temperature is well below freezing for a long enough time.B) Winters are really snowy for a long enough time.C) Melting exceeds snowfall for a long enough time.D) Rocks are being raised by tectonic motions.E) Snowfall exceeds melting for a long enough time.Feedback: Anyone from Erie can tell you that a snowy winter does not guarantee a glacier, and anyone from the permafrost of Siberia could add that cold does not guarantee a glacier. Many high mountains are free of ice, and some warm places are being raised tectonically. The way to make a glacier is to pile up more snow than melts.